The deep water of Eastern Mediterranean Sea is a hotspot for bacterial activity

Eyal Rahav, Jacob Silverman, Ofrat Raveh, Or Hazan, Maxim Rubin-Blum, Christina Zeri, Alexandra Gogou, Martina Kralj, Alexandra Pavlidou, Nurit Kress

Research output: Contribution to journalArticlepeer-review


We investigated the abundance and production of mesopelagic (150–650 m) and bathypelagic (>650 m) bacteria from the poorly-studied Levantine basin (Eastern Mediterranean Sea) during the summers of 2014–2017. We show that the mesopelagic and bathypelagic microbial populations have relatively high cell specific activity, amongst the highest worldwide, likely due to the relatively warm temperatures characterizing these depths in comparison to other oceanic regions. Furthermore, in order to investigate if mesopelagic and bathypelagic microbial populations are limited by the scarce organic carbon substrates in the area, we performed microcosm addition assays of pure glucose (Glu) and/or a mixture of dissolved free amino acids (DFAA). Both the mesopelagic and bathypelagic bacterial populations responded positively to the additions, with bacterial production rapidly increasing within a few hours following the Glu or DFAA amendments. Our results demonstrate that deep-water microbes in the Levantine Basin may be important nutrient recyclers, especially when labile organic carbon is introduced. Our observations may have implications on carbon cycling and sequestration in the oligotrophic Eastern Mediterranean Sea.

Original languageEnglish
Pages (from-to)135-143
Number of pages9
JournalDeep-Sea Research Part II: Topical Studies in Oceanography
StatePublished - Jun 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd

ASJC Scopus subject areas

  • Oceanography


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